Wide-band frequency mixer for diodes



May 4, 1954 H. F. MATARE WIDEBAND FREQUENCY MIXER FOR DIODES Filed Nov. 25, 19.49

.llll/IM A I FII Patented May 4, 1954 UNITED STATE@ A'EENT OFFICE WIDE-BAND FREQUENCY MIXER FOR DIODES France Application November 23, 1949, Serial No. 129,026

Claims priority, application France December 4, 1948 (Cl. Z50-20) 5 Claims.

Crystal-operated frequency-mixers for diodes as used heretofore have the drawbacks of being complicated in construction and useable only in somewhat narrow frequency-bands.

This invention is directed to the provision of a mixer which is particularly handy to operate and is more versatile or universal in its uses, in that it has a wide frequency-band characteristic whereby a given mixer unit is adapted for use in a very wide variety of conditions while the same time retaining the requisite sensitivity in each individual condition of use. In fact, in the frequency mixer forming the subject matter of this invention the sensibility losses do not exceed ten times the power in lcTo for an optimum value of the kIo factor, where k is the Boltzman constant and To is the absolute temperature in Kelvin degrees. It is for this reason that the mixer of the invention may be adequately described as being universal in use.

The frequency mixer of the invention is essentially characterized by the fact that it comprises a central tube which contains the detector and the respective ends of which form the high irequency input and the medium yfrequency output, said tube further containing a choke reactance having a low resistance value and, at the medium frequency output side, a replaceable tuning capacitance, and the said tube being connected with a local oscillator through a variable coupling means and the said choke reactance being Fi connected with a variable short-circuiting means providing for fine adjustment.

Further characteristic features and advantages of this invention will appear from the ensuing description and the accompanying drawings in which one embodiment of the invention is diagrammatically illustrated by way of example only.

In the drawings:

Fig. l is a sectional view of a frequency-mixer constructedaccording to the invention, and

Fig. 2 is an outer View thereof.

As shown, the mixer comprises a central tube I one end 2 of which constitutes the high yfrequency input side with an input plug socket 3 and the other end l! of which constitutes the medium frequency output. Within this tube there is arranged a detector ii which may comprise a crystal diode and which is supported on a central rod 5. a low-resistance choke reactance 'l allowing accurate tuning to be obtained throughout a wide range of frequencies, said reactance being connected to one end of a short-circuiting rod the other end of which is grounded through a con- On this rod there is mounted i nector 9 and over which rod a slider it is movable. 'I'he short-circuiting rod t is located in an externally threaded tube i i over which a nut I2 is threaded; said nut is formed with a circumferential groove i2@ and in this groove a pin ma is engaged, said pin having secured to it the above-mentioned slider i, and a longitudinal groove IIa is formed in the tube il to enable longitudinal displacement of the pin lila thereover. The end of the tube II is sealed by the grounding connector or adaptor 9.

The top of the detector 5 is imbedded and retained in a plug socket I3 adapted to form a tuning capacity for the wide wave band for which the apparatus is constructed. This capacity is removable and may be replaced by a plug socket diifering in length and diameter and suitable for a dierent wide range of frequencies. The plug socket is retained in place by an outer socket it which is screwed onto the medium frequency t of the tube l and is insulated by the separating layer of air between the side surface of the plug socket I3 and the inner surface of the adjacent end of the tube I, and by insulating ring E5.

The energy output from a local oscillator connected with the frequency-mixer through a connector plug socket i5, is variably coupled with said mixer through the medium of a strip l'i mounted on the end of a sliding rod I8 guided in a part of the socket I6. The rod I8 and the strip Il' may be actuated by means of a slidernut i9 screwed over a threaded tube 29 surrounding the rod i8 and the socket Iii and supporting the rod it through the medium of an insulating support 2| (which may also be made of trolitul or the like) rigid with a pin 2 la projecting into a circumferential groove ISa of the slider-nut E9, a longitudinal groove 22 being formed in the tube 29 to permit movement of the pin 2id.

The plug sockets 3 and I are insulated from the tubes i and 29 from which they are respectively supported, by means of insulating bushings 23 and 2s.

The main advantages of a frequency-mixer constructed as above described are the following:

(l) It possesses a wide frequency band. The mixer very successfully operates in a range of from 2G00 to 600() mc. (or wavelengths from l5 to 5 cm.) and successfully in the range of 1500 to 10,009 rnc. (wavelengths from 20 to 3 cm.)

2) rljhe medium frequency output capacity is very readily altered to suit any requisite value;

(3) The variable coupling of the local oscillator only requires operation of a single slider;

(e) The high-frequency detector short-circuit u* current is measured between the medium frequency output and earth, this making it possible to provide a biasing voltage supply;

(5) The input impedance is adjusted through the short-circuit device which is adapted at the same time to earth one side of the detector.

It will be understood that modifications may be made in the constructional details of the device described above and illustrated by Way of example without departing from the general spirit of the invention. rlhus in particular, the actuation of the slider nuts lil and l S could quite conceivably be made through other means than those illustrated.

I claim:

1. In a diode type mixer of the kind described, in combination a straight central tubular body having an input at one end and an output at the opposite end, supporting means extending axially through said body in spaced insulated relation with the walls thereof, a choke reactance of low resistance value mounted on said means towards said input end and a detector mounted on said means towards said output end, said supporting means at said output and comprising one interchangeable electrode of an output capacity, the other electrode of said capacity comprising the adjacent end portion of said tubular body, said interchangeable electrode comprising a plug removably held in the adjacent end portion of said tubular body and insulated therefrom, an input plug socket formed in the input end of said supporting means, an inner output socket element formed in the outer projecting end of d said interchangeable electrode, means screwable over the output end of said body to hold said removable plug in place and constituting the outer element for said output socket, a irst lateral tubular extension projecting from said body between said choke reactance and detector and provided with variable coupling means for a local oscillator therein, and a second lateral tubular extension projecting from said body adjacent said reactance and means associated with said second extension for variably adjusting said reactance.

2. Mixer as in claim 1 wherein said means associated with said second extension comprise a short-circuiting rod through said extension in contact engagement with said reactance at the inner end thereof and with the outer end or" said extension at the outer end thereof, and actuating means operable from outside said extension for connecting a variable point of said rod with the wall of said extension.

3. In a diode mixer of the kind described, a straight tubular body having an input at one end and an output at the opposite end, a straight central rod extending axially of the body from the input end and terminating at a distance from the output end of the body, insulating means supporting said rod at the input end, a plug extending into the output end portion of the body and comprising an interchangeable inner electrode of an output capacity, the other electrode of which comprises the adjacent end portion of the body, means including at insulator for removably holding said plug in spaced relation to the wall of said body and insulated therefrom, a detector supported by and between the central rod and said plug, a reactance on the central rod between the detector and the input end of the body, a first branch tube extending laterally from and opening into the body between said detector and said reactance, variable coupling means for a local oscillator in said branch tube, a second branch tube extending laterally from and opening into the body adjacent said reactance and means associated with said second extension for varying said reactance.

4. In a diode mixer of the kind described, a. straight tubular body portion having an input at one end and an output at the opposite end, a straight central rod extending axially of the body from the input end to a point spaced from the output end of the body, insulating means supporting said rod, a plug extending into the output end portion of the body and comprising an interchangeable inner electrode of an output capacity, the other electrode of which comprises the adjacent end portion of the body, a collar readily detachably secured to the body to hold said plug removably in position in the end of the body, an insulating ring between the plug and said collar, the wall of said body being spaced from the plug when the latter is positioned in the body, a detector supported by and between the central rod and said plug, a reactance on the central rod between the detector and the input end of the body, a rst branch tube extending laterally from and opening into the body between said detector and said reactance, variable coupling means for a local oscillator in said branch tube, a second branch tube extending laterally from and opening into the body adjacent said reactance and means associated with said second extension for varying said reactance.

5. In a diode mixer of the kind described, a straight tubular body portion having an input at one end and an output at the opposite end, a straight central rod extending axially of the body from the input end to a point spaced from the output end of the body, insulating means supporting said rod, a plug extending into the output end portion of the body and comprising an interchangeable inner electrode of an output capacity, the other electrode of which comprises the adjacent end portion of the body, means including an insulator for removably holding said plug in spaced relation to the wall of said body and insulated therefrom, a detector supported by and between the central rod and said plug, a reactance on the central rod, a rst branch tube extending laterally from and opening into the body between said detector and said reactance, variable coupling means for a local oscillator in said branch, a second branch tube extending laterally from and opening into the body adjacent said reactance, a short-circuiting rod disposed in said second branch, a short-circuiting slider on said short-circuiting rod and means external of said second branch for adjustably moving the slider along the short-circuiting rod.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,408,420 Ginzton Oct. l, 1946 2,433,387 Mumford Dec. 30, 1947 2,436,830 Sharpless Mar. 2, 1948 2,455,657 Cork et al Dec. 7, 1948 v 2,456,305 Nelson Dec. 14, 1948 

